1. Technical Field of the Invention
The present invention relates to a frequency characteristics control device suitable for application to an audio apparatus such as a mixer that mixes audio signals, and more particularly to a frequency characteristics control device that can accentuate an audio signal of a solo part such as vocal relative to an audio signal of a back part such as an accompaniment instrument.
2. Description of the Related Art
A mixer that adjusts characteristics of a plurality of audio signals inputted from microphones or the like through a plurality of input channels and mixes the adjusted audio signals on a plurality of mix buses and outputs the mixed signal is known in the art (for example, see Patent Reference 1).
A technology for removing a specific audio signal already known from a mixed audio signal is also known (see Patent Reference 2). In this technology, a specific acoustic amplitude spectrum is extracted from the specific audio signal that the user desires to remove, and a mixed acoustic amplitude spectrum is extracted from the mixed audio signal produced through mixture of the specific audio signal and other audio signals. Then, the removal extent of the specific signal is set, assuming that the mixed audio signal and the specific audio signal are distributed with the same probabilities with the phase difference between the mixed audio signal and the specific audio signal being in a range of 0 to 360 degrees, and the specific acoustic amplitude spectrum is exchanged based on the setting to remove the specific acoustic amplitude spectrum from the mixed acoustic amplitude spectrum.
[Patent Reference 1] Japanese Patent Application Publication No. 2006-270507
[Patent Reference 2] Japanese Patent No. 4274418
When an audio signal of a specific channel (for example, a vocal sound or a musical instrument sound of a solo part) and audio signals of other channels (for example, musical instrument sounds of accompaniment parts) are mixed and outputted, the user may desire to perform adjustment so as to selectively emphasize the audio signal of the specific channel. In this case, the user desires only to accentuate a specific audio signal from an audio signal as opposed to the prior art which removes a specific audio signal. The prior art of Patent Reference 2 only removes an audio signal, and its process is very complicated.
Of course, in the case of the conventional mixer described in Patent Reference 1, it is possible for a skilled operator to accentuate an audio signal of a specific channel by adjusting each channel since a signal level, frequency characteristics, and the like of each of a plurality of channels are adjustable. However, if an unskilled operator performs such adjustment, there is a problem such as destruction of overall balance.